1. Field of the Invention
The present invention is directed to a regeneration system to regenerate glycol for a dehydrator that removes water vapor from a gas stream.
2. Prior Art
Water vapor is an undesirable impurity in a gas stream. When the gas is compressed or cooled, the water vapor reverts to a liquid or solid phase. Liquid water can accelerate corrosion in pipelines and reduce the gas transmission efficiency. Water in the solid state forms icy hydrates, which can plug valves, fittings, and gas lines. To prevent these difficulties, some of the water vapor must be removed from the gas stream before it is transported in transmission lines.
A dehydrator removes water vapor from a gas stream produced from a natural gas well. There are a number of methods to accomplish dehydration, one of which is absorption. A hygroscopic liquid is used to remove the water vapor from the gas. Diethylene and triethylene glycol are two of the liquids often used for gas dehydration.
In the dehydration process, wet gas from the well is directed into the bottom of an absorber tank or chamber. The gas flows upward through a packed bed or through a series of bubble cap or valve trays filled with glycol where intimate contact is made. The gas gives up water vapor to the glycol. The dry gas leaves the absorber where it may flow into the sales or transmission line.
Dry, lean concentrated glycol is continuously pumped into the top of the absorber. As the glycol moves downward, it absorbs water vapor from the rising gas stream. The water-rich glycol is removed at the bottom of the absorber. The glycol is regenerated by removing the water vapor so that it may be reused.
A pump may be used to move glycol through the system. A gas-glycol pump is commonly used. The gas-glycol powered pump utilizes rich glycol under pressure in the absorber to furnish part of its required driving energy. Since the pump cannot get more glycol back than it pumped over, a supplemental volume is needed to provide the driving force. Gas, under pressure from the absorber, is taken in with the rich glycol to supply this additional volume.
The rich glycol, having gas entrained therein from the pump, is pumped to a reboiler where it is heated to a temperature to vaporize water in the glycol. A glycol-gas separator is sometimes employed to separate gas from the glycol prior to introduction into the reboiler. Additionally, the distillation process may be modified by the use of a stripping gas to strip additional water vapor.
A stripper or still column is normally located on top of the reboiler to separate the water and glycol. Packing is often used in the still column to encourage coalescence.
A reflux coil or other reflux mechanism may be utilized to condense vapor in the still column. An atmospheric condenser may be used to cool the steam vapors and recover the entrained glycol held by the gas.
In the present invention, the reflux coil or reflux mechanism as well as the glycol-gas separator have been eliminated. In their place, a reflux chamber jacket has been provided on top of the still column which utilizes cool rich glycol as a reflux medium. Additionally, the reflux jacket chamber is used to separate gas from the rich glycol. The separated gas is then utilized as a stripping gas in the reboiler.
Accordingly, it is a principal object and purpose of the present invention to provide a regeneration system employing a reflux jacket chamber that separates and captures waste gas introduced by the pump and flash gas dissolved in the glycol.
It is a further object and purpose of the present invention to provide a regeneration system employing a reflux jacket chamber that separates gas from glycol which operates at atmospheric pressure.
It is a further object and purpose of the present invention to provide a regeneration system employing a reflux jacket chamber that separates gas from glycol wherein the separated gas is used as a stripping medium to strip vapor from glycol.